John Lewis, the legal director of Marriage Equality USA, said North Carolina's ban is Reason No. 1 why Obama needs to take a stand now.

"I think this vote makes crystal clear that the President of the United States needs to stand up for the freedom to marry for all American citizens," Lewis told Business Insider.

"What I'm thinking of tonight is the gay kid growing up in North Carolina, who's just been told that he can't fulfill his dreams. The President of the United States needs to stand up for that kid. He needs to stand up for Americans and say that every single American has inherent freedom to marry the person they love and pursue their happiness."

Fischer said this issue has become a nightmare for Obama. He called it the "third rail" of the Obama campaign, meaning it's too sensitive of an issue for Obama to touch either way. Whichever way he handles it, he might now lose some votes if the issue keeps up in prominence throughout the campaign.

"Obama had a trip to North Carolina scheduled for today, and he canceled it," Fischer told Business Insider. "I believe he canceled it because I believe he simply does not want to face any awkward questions about the institution of marriage.

"This is a major problem for him. Because clearly, the American people who are going to the polls in November are not with him on the issue of marriage," Fischer said, adding that "natural marriage is 32-0" in state votes.

Lewis, of Marriage Equality USA, agreed — but that's about where it stopped. He said the group was "deeply disappointed" that North Carolina had passed a law that "deprives basic couples of their rights."